How Does a Cesspool Work?

Cesspools are simple in design but crucial in function. They consist of a large underground tank typically made of concrete or fiberglass. The tank is buried in the ground and has one or more openings for pipes that connect to the building’s plumbing system. When wastewater from 

the building flows into the cesspool, it separates into three layers:

1. Scum: The top layer of the cesspool is made up of oils, fats, and other floating materials. This layer is lighter than water and floats on the tank surface.
2. Effluent: The middle layer of the cesspool is made up of wastewater and other liquid materials. This layer is denser than scum but lighter than sludge.
3. Sludge: The bottom layer of the cesspool is made up of solids and other heavy materials that sink to the bottom of the tank. This layer is denser than scum and effluent.

As wastewater enters the cesspool, it decomposes naturally. Bacteria in the tank break down solids and other organic materials, converting them into gasses like methane and carbon dioxide. The gasses rise to the top of the tank and are released into the air through a vent pipe.

Over time, the sludge layer in the cesspool will build up and reduce the tank’s wastewater capacity. When the tank is full, it must be pumped out to remove the sludge and scum layers. This process should be done regularly to prevent backups and ensure the cesspool functions correctly.